In many projection lamp units which include a preformed glass reflector and projection lamp capsule (e.g., tungsten halogen) therein, the lamp capsule is retained in alignment within the reflector by employing a suitable cement (e.g., Sauereisen) within the reflector and about the lamp's sealed end. Examples of such arrangements are shown in U.S. Pat. Nos. 3,314,331 (Wiley) and 3,639,750 (Anthonijsz). Use of cement or a similar permanent-type bonding agent prohibits separation of the lamp capsule and reflector in the event that replacement of either of these components is necessary. In almost all cases, it is only the incandescent lamp capsule which fails and needs replacement. The aforementioned permanent bond between lamp and glass reflector was believed essential to assure precise alignment between said components and between these members and other elements (e.g., film gate, projection lens) within the system using the lamp unit. In those systems not utilizing such elements, precise lamp-reflector alignment is believed essential to provide accurately directed light onto the object(s) being illuminated. This is particularly true in track and recessed accent lighting. Alignment between the reflector and lamp was usually achieved using a precisioned instrument whereupon the assembled unit was ready for being inserted within a respective socket holder arrangement, such as shown in U.S. Pat. No. 3,789,212 (Wagner). This latter positioning is usually accomplished by the projector's operator.
Mandatory replacement of both lamp and glass reflector has therefore resulted in unnecessary waste of material which in turn has added appreciably to the overall cost of operating such systems.
The projection unit of U.S. Pat. No. 4,156,901 (Haraden et al) was designed to eliminate the above undesired requirement by providing a retention member which is removable from within the reflector yet which also assures positive alignment of the unit's incandescent lamp within the reflector when said lamp is positioned therein. The retention member is secured to the lamp's sealed end and comprises a metallic "can", a preformed component of insulative material such as ceramic, or a combination of both. One particular disadvantage of the unit described in U.S. Pat. No. 4,156,901 is the requirement for providing grooves, slots, etc. within the reflector's elongated neck portion to accommodate the retention member, which in turn included protruding tabs or similar items for being finally positioned within these grooves. Yet another disadvantage of the unit of U.S. Pat. No. 4,156,901 is that the reflector opening to accommodate the unit's retention member must be relatively large, thus reducing the available reflective surface area of the reflector.
The projection unit described in U.S. Pat. No. 4,219,870 (Haraden et al) was designed as an improvement over the aforedescribed unit of U.S. Pat. No. 4,156,901 by providing means whereby the retention member having the sealed end of the lamp therein may be removed from the front, concave reflecting portion of the glass reflector. The method of removal for these components in U.S. Pat. No. 4,156,901 is through the rear (neck) opening of the reflector. Rearward removal proved difficult in the complete system due to the typically limited accessibility in this region of the system. In U.S. Pat. No. 4,219,870, the resulting unit also requires a metallic "can" on the end of the lamp capsule, as well as the aforementioned grooved, slots, etc. within the opening in the reflector's neck. This opening is substantially smaller, however, than that in U.S. Pat. No. 4,156,901 but in order to accomplish this it is necessary to provide a second, external springlike retention member, as well as grooves in the neck's external surface to accommodate this second member.
In addition to the above, several versions of various front-loading projection units are described in U.S. Pat. Nos. 4,376,967 (Hough), 4,394,189 (Hough et al), and 4,403,276 (Blaisdell), all of which are assigned to the same assignee as the instant invention. All of these units require provision of slots or grooves within the glass reflector's neck portion in order to effect proper alignment of the lamp capsule therein. In addition, all require utilization of a metallic "can" or similar component secured to the end of the capsule (about the sealed end of the lamp itself) which must be inserted within the reflector's neck. As also in the case of the above units, this "can" member includes protuberances or similar projecting portions in order to align the capsule, said protuberances being slidably positioned within the corresponding grooves or slots of the reflector. Still further, the above units require some additional means of accomplishing capsule securement, such as a threaded nut, wireform, or locking cantilever spring member.
Yet another embodiment of a projection unit having a separable lamp capsule is described in U.S. Pat. No. 4,384,319 (Blaisdell et al), which is also assigned to the same assignee as this instant invention. In this unit, the capsule also includes an attached metallic "can" in addition to a pair of projecting flanges which slidably engage both the neck of the reflector and upstanding rear part of the unit's metallic U-shaped holder. Once the capsule was inserted, it is necessary U.S. Pat. No. 4,384,319 to thereafter attach the preferred socket component, which itself constitutes a separate part of the system. It is thus necessary in this unit to precisely locate the flange portions relative to the capsule's filament structure in order to provide proper filament orientation within the reflecting region of the reflector. Such a procedure is understandably both costly and time-consuming.
In U.S. Pat. Nos. 4,389,700 (Blaisdell et al) and 4,390,935 (Audesse et al), there are described two versions of projection units wherein some form of ejector (e.g., pivotal rod, slidable bar member) is utilized to engage the sealed end of the capsule's envelope and eject the capsule through the reflector's forward opening. It is thus necessary for the system operator to have access to the portion of the unit-holder assembly behind the retained reflector in order to accomplish lamp ejection.
In accordance with the teachings of the instant invention, there is defined a projection lamp unit which enables facile ejection of the lamp capsule through the forward opening of the reflector without the need for an ejector bar or similar mechanism, a metallic "can" or the like member secured to the capsule, or an external retention means or the like which must be removably located on the reflector (requiring external slots in the reflector's neck portion), yet which is able to provide precise alignment of the capsule relative to the reflecting surfaces of the reflector. It is believed that such a lamp unit would constitute a significant advancement in the art.